This project examines the impact of infection with human herpesvirus 8 (Kaposi's sarcoma-associated herpesvirus) as well as Epstein-Barr virus infection on the risk of developing human lymphomas. The study employs transplantation of human peripheral blood leukocytes from normal donors to SCID mice, a reliable model for predicting the risk of post-transplant lymphoproliferative disease and has led to the development of autologous cytotoxic T lymphocyte treatment of this condition.